d and f-Block elements Flashcards for NEET — 21 cards

First 8 of 21 d and f-Block elements flashcards

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1. Card 1 of 21

   Why are Zinc (Zn), Cadmium (Cd), and Mercury (Hg) not considered true transition elements?

   Hint: Transition elements require partially filled d-orbitals.

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   Answer

   Because they have completely filled d-orbitals ($d^{10}$) in their ground state as well as in their common oxidation states.

2. Card 2 of 21

   Write the anomalous electronic configurations of Chromium (Cr, Z=24) and Copper (Cu, Z=29).

   Hint: Half-filled and fully-filled stability shifts an s-electron to the d-subshell.

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   Answer

   Chromium: $[Ar] 3d^5 4s^1$ Copper: $[Ar] 3d^{10} 4s^1$

3. Card 3 of 21

   Describe the trend of Atomic Radii across the 3d transition series (from Sc to Zn).

   Hint: Decrease -> Constant -> Increase.

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   Answer

   1. Decreases initially (Sc to Mn) due to increasing effective nuclear charge. 2. Remains almost constant (Fe, Co, Ni) as shielding by d-electrons balances nuclear charge. 3. Increases slightly at the end (Cu, Zn) due to increased interelectronic repulsions in the filled d-orbitals.

4. Card 4 of 21

   Which element in the 3d series exhibits the maximum number of oxidation states, and what is its highest state?

   Hint: It has the configuration 3d5 4s2, allowing it to lose up to 7 electrons.

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   Answer

   Manganese (Mn) exhibits the maximum number of oxidation states, ranging from +2 to +7.

5. Card 5 of 21

   Which two elements in the 3d series show only a single non-zero oxidation state?

   Hint: Sc reaches noble gas config at +3; Zn reaches stable d10 at +2.

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   Answer

   Scandium (Sc) shows only +3. Zinc (Zn) shows only +2.

6. Card 6 of 21

   What is the most important consequence of the Lanthanoid Contraction on the transition metals of the 4d and 5d series?

   Hint: Zr (Z=40) and Hf (Z=72) are chemical twins.

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   Answer

   The atomic radii of the second (4d) and third (5d) transition series elements become almost identical (e.g., Zr and Hf have almost the same radius). This makes them exist together in nature and very difficult to separate.

7. Card 7 of 21

   Why are most transition metal ions colored in aqueous solutions?

   Hint: Electrons jumping between split d-orbitals.

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   Answer

   Due to the presence of unpaired d-electrons which undergo d-d transitions. They absorb light of a certain wavelength from the visible region to promote an electron, transmitting the complementary color.

8. Card 8 of 21

   Potassium permanganate ($KMnO_4$) is intensely purple, yet $Mn^{7+}$ has a $d^0$ configuration. Why is it colored?

   Hint: This is a classic NEET exception! No d-electrons = no d-d transition.

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   Answer

   The color is due to Ligand-to-Metal Charge Transfer (LMCT), not d-d transitions. An electron is temporarily transferred from the oxygen ligand to the empty d-orbital of manganese.